首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   257篇
  免费   0篇
  国内免费   1篇
电工技术   30篇
化学工业   32篇
金属工艺   5篇
机械仪表   5篇
建筑科学   1篇
能源动力   3篇
轻工业   10篇
无线电   70篇
一般工业技术   22篇
冶金工业   67篇
原子能技术   9篇
自动化技术   4篇
  2023年   1篇
  2022年   1篇
  2021年   3篇
  2020年   2篇
  2019年   4篇
  2018年   4篇
  2017年   1篇
  2016年   3篇
  2015年   2篇
  2014年   5篇
  2013年   11篇
  2012年   9篇
  2011年   10篇
  2010年   4篇
  2009年   10篇
  2008年   4篇
  2007年   8篇
  2006年   7篇
  2005年   1篇
  2004年   5篇
  2003年   3篇
  2002年   6篇
  2001年   8篇
  2000年   6篇
  1999年   5篇
  1998年   36篇
  1997年   20篇
  1996年   11篇
  1995年   12篇
  1994年   3篇
  1993年   7篇
  1992年   3篇
  1991年   4篇
  1990年   1篇
  1989年   3篇
  1988年   3篇
  1987年   8篇
  1986年   5篇
  1985年   2篇
  1984年   4篇
  1983年   1篇
  1982年   2篇
  1978年   1篇
  1977年   3篇
  1976年   3篇
  1972年   1篇
  1971年   1篇
  1970年   1篇
排序方式: 共有258条查询结果,搜索用时 15 毫秒
41.
The microstructural properties of the β-FeSi2/FeSi structure prepared from a molten salt have been characterized using transmission electron microscopy (TEM). The β-FeSi2 films were grown on FeSi substrates at the heat treatment temperature of 900 °C from 1 min to 24 h using the molten salt technique. It is found that the films consisted of a thin surface layer and a thick underlying layer with columnar-shaped domains. The crystallographic directions of the domains are mostly randomly oriented. The β-FeSi2 domains in the film, however, have specific crystallographic orientation relationships with the adjoining domains and the FeSi substrate. A high density of the stacking faults on the β-FeSi2 (100) planes was also observed through the films. Moreover, the growth evolution of the β-FeSi2 domains, the defect characteristics and the formation mechanism of the defects are discussed.  相似文献   
42.
β-FeSi2 layers have been successfully grown using a molten salt method for the first time. It was found that single phase and homogeneous β-FeSi2 layers with a columnar domain structure can be grown on FeSi substrates. The layer thickness was demonstrated to be controllable by the growth temperature and time, and was diffusion controlled. It was shown that the layers were void- and crack-free compared to similar layers grown on Fe substrates: this difference is explained in terms of Fe diffusion. This vacuum-free simple growth technique is useful for the fabrication of large area semiconductor devices at low cost.  相似文献   
43.
BACKGROUND: Balloon injury models in rat have shown enhanced expression of ACE in the developing neointima. However, neointimal lesions in human coronary arteries are complex due to atherosclerosis and different types of wall laceration. This study was designed to investigate whether ACE is present in the neointima of humans, including patients with restenosis after percutaneous transluminal coronary angioplasty (PTCA). METHODS AND RESULTS: Thirty-seven sites with angioplasty injury, obtained at autopsy, were studied using immunocytochemical techniques. Sites with injury limited to a fibrous plaque and those with injury extending into the media (<2 months after PTCA) showed fibrocellular repair tissue composed mainly of smooth muscle cells that were distinctly positive for ACE. In cellular reactions at the site of injury limited to the atheromatous plaque (<2 months after PTCA), the expression of ACE appeared first in accumulated macrophages; once smooth muscle cells appeared in the repair tissue, they also expressed ACE. At a later stage (3 months after PTCA), the number of cells with ACE expression decreased markedly; from 7 months on, ACE was no longer expressed within the repair tissue. Basically, there were no differences with regard to ACE expression during the healing process after PTCA between segments with and those without angiographic evidence of restenosis. CONCLUSIONS: These results show that PTCA injury in humans results in upregulation of ACE at sites of active repair and, therefore, ACE could play an important role as one of the mediators of the healing process after PTCA.  相似文献   
44.
A new spectral attenuation measurement system using a Fourier transform spectrometer is developed. The Fourier transform spectral attenuation measurement (FT-SAM) system makes the signal acquisition time for a wide wave-length range of 1.0?4.2? much shorter than measurement with a conventional dispersive spectral attenuation measurement system. The spectral attenuation for a fluoride glass single-mode fibre, with a minimum loss of 3±1 dB/km at 2.5?m, is measured with this system.  相似文献   
45.
Clinical diagnosis of canine nasal mite (Pneumonyssoides caninum) infection is difficult due to the mite's location in the caudal nasal cavity and frontal sinuses. The current study was performed to evaluate the efficacy of milbemycin oxime in treating dogs with nasal mite infection. A prospective open uncontrolled study included 20 dogs with case histories indicating possible nasal mite infection. Inclusion criteria consisted of either nasal mites being demonstrated (group 1, four dogs), or suspicious clinical signs with no other apparent causes, combined with eosinophilia (group 2, 16 dogs). Milbemycin oxime 1 mg/kg was given orally three times at 10-day intervals. In 17 (85 per cent) dogs, clinical signs resolved completely following milbemycin therapy; within 10 days of the first treatment in 13 cases (group 1, four dogs; group 2, nine dogs) and within 14 days in four cases. In the remaining three dogs clinical signs persisted but were diminished.  相似文献   
46.
Rifampicin synoviorthesis has been empirically used for the treatment of haemophilic synovitis for some time. This paper reports on the experience of three Latin American centers with this treatment and compares it with radioactive synoviorthesis results. Chemical synoviorthesis with rifampicin is best indicated in younger patients (< 15 years) and small joint (ankles and elbows).  相似文献   
47.
Dolichol-phosphate-mannose (Dol-P-Man) serves as a donor of mannosyl residues in major eukaryotic glycoconjugates. It donates four mannosyl residues in the N-linked oligosaccharide precursor and all three mannosyl residues in the core of the glycosylphosphatidylinositol anchor. In yeasts it also donates one mannose to the O-linked oligosaccharide. The yeast DPM1 gene encodes a Dol-P-Man synthase that is a transmembrane protein expressed in the endoplasmic reticulum. We cloned human and mouse homologues of DPM1, termed hDPM1 and mDPM1, respectively, both of which encode proteins of 260 amino acids, having 30% amino acid identity with yeast Dpm1 protein but lacking a hydrophobic transmembrane domain, which exists in the yeast synthase. Human and mouse DPM1 cDNA restored Dol-P-Man synthesis in mouse Thy-1-deficient mutant class E cells. Mouse class E mutant cells had an inactivating mutation in the mDPM1 gene, indicating that mDPM1 is the gene for class E mutant. In contrast, hDPM1 and mDPM1 cDNA did not complement another Dol-P-Man synthesis mutant, hamster Lec15 cells, whereas yeast DPM1 restored both mutants. Therefore, in contrast to yeast, mammalian cells require hDPM1/mDPM1 protein and a product of another gene that is defective in Lec15 mutant cells for synthesis of Dol-P-Man.  相似文献   
48.
49.
50.
We measured the interfacial tension of 3 He-4 He mixtures under pressure of 21 atm down to about 0.2K by using the resonance of the interfacial wave and found that the decrease from absolute zero is proportional to T2 up to about 0.4 K. From the simple extrapolation of this T2-dependence the interfacial tension at absolute zero is obtained as i (0) = 19.3 ± 1.3 mdyne/cm. Compared with saturated vapor pressure, the interfacial tension at absolute zero decreases by about 20%, and the coefficient of the T2-dependence does not depend strongly on pressure. The large T2-dependence both at saturated vapor pressure and at 21 atm may be attributable to the change in density difference between the two phases.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号